If Adventure games are not to your liking, then come and try out this highly energetic shoot 'em up titled ' Operation Fungus ', developed by Jani Nykänen. This game is a 2D arcade like shooter, whereby you have to kill enemies to obtain not only a high score, but to later use to upgrade your skills! Also, as the developer describes, In each state you must fill the power gauge before you can fight the boss monster. The more enemies you kill in row, the more crystals you gain, and thus, the faster the power gauge will become full. But beware, if you take damage, you will lose 10% of the power!
Not only is the game free to play, but there are loads of enemies, plenty of action to be had, a cool soundtrack by Oskari "h0dari" Romo, multiple levels with different themes such as the snow level and available for both PC and Linux. For those of you who want more, the final version will have eight different missions!
Links : 1) Source 2) Download